Transformer or choke having an air gap



1954 E. w. VAN HEUVEN TRANSFORMER OR CHOKE HAVING AN AIR GAP Filed Nov. 17, 1950 ll/IllIlI/I/rl/l/l 'IIIIIIIII IIIII II I OMOMOMO 0 INVENTOR.

'ENGELBERT W. VAN HEUVEN AGENT TRANSFORMER 0R CHOKE HAVING AN AIR GAP 'Engelb art Wiegman van Heuven, -Eindhoven, Netherlands,

:assignor to Hartford National Bank and Trust'Comgpany, Hartford, Conn., as trustee Application November'17, 1950,Serial No. 196,150

Claims priority, appiication Netherlands December-9, 1949 6 Claims. (Cl. 336-67) The invention relates to an iron'cored transformer or choke having an air-gap.

Such inductors produce oscillations the lowest frequency of which corresponds to double the frequency of the alternating supply current. These oscillations may be transmitted, by way of the stay members of the apparatus, to the mounting surface, which is thus enabled to radiate the oscillations in the form of sound.

The invention has for its object to reduce the oscillaion transmission from the apparatus to the mounting surace.

According to the invention, the stay members of the apparatus are secured only to areas of the ferromagnetic core, which, in the resiliently suspended condition of the apparatus, owing to the excitation of the inductor, per form movements which in no direction exhibit an amplitude in excess of 0.2 (micron) and which are preferably smaller than 0.1,u or even less than 0.05 r. This results in that substantially no oscillations are transmitted to the body to which the apparatus is secured, so that this body is prevented from acting as a sound board. In the condition of resilient suspension with the usual excitation, the areas intended for connection to the stay members may be tested concerning oscillation amplitude, for example, with the use of an electric oscillation pick-up.

According to a preferred embodiment of the invention, the areas of connection to the stay members are located on a line which passes through the center of gravity of the apparatus lying in the ferromagnetic part and which is at right angles to the plane of the magnetic lines of force in the ferromagnetic part.

The invention will now be described in detail with reference to the accompanying drawing in which:

Fig. l is a plan view of a mounting assembly for an inductor according to the invention; and

Fig. 2 is a sectional view taken along the line 11-11 of Fig. 1.

In Fig. 1 the core comprises a pile of iron sheets each of which is in the form of two E-characters facing one another, the central limbs 1 and 2 merging into one another and provision being made between the outer limbs 3, 4 and 5, 6 of air-gaps 7, 8. The apparatus comprises two coils 9, 10, which are arranged on the outer limbs.

The center of gravity of the apparatus is at the center of the common central bar 1, 2. Obviously, during operation this point and the similar points 11 in the various iron sheets do not perform any motion in the condition of resilient suspension so that the apparatus can be secured in situ so as to be free from vibrations.

As can be seen from Fig. 2 at the area of the points 11 the iron sheet system is apertured and through these apertures a bolt 12 is passed by means of which the apparatus is secured to a supporting member 13. Arranged between the bottom layer of the iron-sheet system and the supporting member is a spacer 14 in the shape of a hollow cylinder surrounding the bolt.

It is obvious that even with other forms of the ferromagnetic part of a transformer or choke it is possible to ascertain points which, during operation, in the condition of resilient suspension of the apparatus, perform substantially no movements, owing to internal forces and which are thus suitable as areas of connection to the stay members of the apparatus concerned.

While the invention has been described with specific application and in specific embodiment, other modifications thereof will appear radily apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. An inductor assembly comprising a closed ferromagnetic core having outer limb portions and a center limb portion defining two windows 'in the core, each of said outer limbs having an air-gap'therein, a coil wound on each of said outer limb portions, and a supporting member securing said core .to a base secured only to an area defined within said center'lirnb portion which exhibits in any direction, when said core is resiliently suspended, 'a movement having an amplitude which is less than'0.2 t when an alternating current of given frequency is flowing through one of the coils, said core and coils being completely spaced from said base and being attached to said base solely by said supporting member, whereby static vibration-free mounting of said inductor assembly is obtained.

2. An inductor assembly comprising a closed ferromagnetic core having outer limb portions and a center limb portion containing the center of gravity of said core, said center limb and said outer limbs defining two windows in the core, each of said outer limbs having an air-gap therein, a coil wound on each of said outer limb portions, and a supporting member securing said core to a base secured only to an area containing a line passing through the center of gravity of the core and at right angles to the plane of the magnetic lines of force in the core, said area exhibiting in any direction, when said core is resiliently suspended, a movement having an amplitude which is less than 0.2 when an alternating current of given frequency is flowing through one of the coils, said core and coils being completely spaced from said base and being attached to said base solely by said supporting member, whereby a static vibrationfree mounting of said inductor assembly is obtained.

3. An inductor assembly comprising a closed ferromagnetic core comprising a pair of opposed generally E- shaped parts forming two outer limb portions each having air-gap therein, and a unitary center limb portion, the outer and center limb portions together defining two windows in the core, a coil wound on each of said outer limb portions, and a supporting member securing said core to a base secured at one end only to an area containing the center of the center limb portion and extending at right angles thereto, said area exhibiting in any direction, when said core is resiliently suspended, a movement having an amplitude which is less than 0.2 when an alternating current of given frequency is flowing through one of the coils, said core and coils being completely spaced from said base and being attached to said base solely by said supporting member, whereby a static vibration-free mounting of said inductor assembly is obtained.

4. An inductor assembly comprising a closed ferromagnetic core comprising a plurality of stacked E-shaped stampings arranged in opposing groups and united to form a core having two outer limb portions each having an air-gap therein and a unitary center limb portion defining with the outer limb portions two windows in the core, a coil wound on each of said outer limb portions, and a supporting member securing said core to a base secured at one end only to an area containing the center of the center limb portion and extending at right angles thereto, said area exhibiting in any direction, when said core is resiliently suspended, a movement having an amplitude which is less than 0.2 when an alternating current of given frequency is flowing through one of the coils, said core and coils being completely spaced from said base and being attached to said base solely by said supporting member, whereby a static vibration free mounting of said inductor assembly is obtained.

5. An inductor assembly comprising a substantially closed ferromagnetic core having an air-gap therein, a coil winding on a portion of said core, and a supporting member secured at one end to a base and at the other end only to an area of said core free of windings which exhibits, in any direction, when said core is resiliently suspended, a movement having an amplitude which is less than 0.2 when an alternating current of given frequency is flowing through the coil, said core and coil being completely spaced from said base and being attached to said base solely by said supporting member, whereby a static vibractlion-free mounting of said inductor assembly is obtaine 6. An inductor assembly comprising a substantially closed ferromagnetic core having a given center of gravity and an air-gap therein, a coil on a portion of said core adjoining an area in closed proximity to the center of gravity of the core thereby leaving that area free of coil windings, and a supporting member secured at one end to a base and at the other end only to an area of the core free of windings and in close proximity to the center of gravity of the core, said area of said core exhibiting in any direction, When said core is resiliently suspended, a movement having an amplitude which is less than 0.211. when an alternating current of given frequency is flowing through the coil, said core and said coil being completely spaced from said base and being attached to said base solely by said supporting member, whereby a static vibration-free mounting of said inductor assembly is obtained. 1

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 400,515 Thomson Apr. 2, 1889 1,897,249 Fleming Feb. 14, 1933 2,445,088 Schilling July 13, 1948 FOREIGN PATENTS Number Country Date 324,998 Germany Mar. 20, 1919 

